And Emma Cunliffe is calling for NSW to introduce the same ''last resort'' mechanism that was used in the Northern Territory to quash Lindy Chamberlain's murder conviction.

The attack on the reliability of expert evidence in Folbigg's trial follows a court ruling on Friday allowing Jeffrey Gilham a retrial on his charge of murder, and possibly even an acquittal, after evidence from experts was found to have been flawed.

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The claims by Dr Cunliffe in her book Murder, Medicine and Motherhood stand against the combined weight of the jury verdict in Folbigg's 2003 trial and two unsuccessful appeals.

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The arguments also seek to address the damning impression made by Folbigg's diaries, in which she wrote of her third child Sarah: ''I know I was short tempered and cruel sometimes to her & she left. With a bit of help.''

Free after three years ... Jeffrey Gilham walks out of court on Friday with his wife Robecca. Photo: Dallas Kilponen

Folbigg was the unremarkable Singleton mother whose trial became a media sensation when she was charged with killing Caleb, Patrick, Sarah and Laura between 1989 and 1999. The children were aged 19 days, eight months, 10 months and 19 months when they died. At its simplest, Dr Cunliffe believes that because no cause of death could be established for

Folbigg's four children, there was never enough evidence to convict her of their murders.

And she says in the absence of medical evidence and a confession, circumstantial evidence from Folbigg's diaries and her husband, Craig, was not enough to convict her.

''At the end of the day I felt that the diaries worry me, but they don't satisfy me beyond a reasonable doubt,'' she said.

She argues medical experts at the trial failed to give evidence that fully reflected the prevailing uncertainty in the scientific community about repeated unexplained infant deaths in a single family.

And she says the experts' evidence became misleading to the extent ''it was unreliable under evidentiary rules''. ''They gave a very incomplete account of the medical research that then existed,'' Dr Cunliffe said.

Folbigg is serving a reduced sentence of 25 years in protective custody at the Silverwater women's jail, where her only visitors are Salvation Army officers and a few friends. She has maintained her innocence, writing in a letter quoted in the book Inside Their Minds: Australian Criminals: ''I'm simply waiting for the truth to be seen or uncovered or proven.''

Dr Cunliffe, who spoke in Sydney on Saturday at a conference about the use of expert evidence, started her research for a doctorate with fixed views about Kathleen Folbigg.

''I came to the case believing her to be guilty,'' Dr Cunliffe, an assistant professor of law at the University of British Columbia in Canada, said in an interview.

''It was really the process of investigation that made this thing fall apart for me.''

Dr Cunliffe's views have won support from prominent forensic pathologists, who also believe a review of Folbigg's conviction should be considered by the NSW Attorney-General, Greg Smith.

Professor John Hilton, a former director of the NSW Institute of Forensic Medicine, was a prosecution witness in the Folbigg trial who gave evidence about the post-mortem examination he conducted on Sarah.

''I think Emma has done a very good job. Her book is a valuable contribution to this whole matter and is deserving of notice by the relevant authorities,'' Professor Hilton said.

Professor Stephen Cordner, the director of the Victorian Institute of Forensic Medicine, has reviewed the book for the Australian Journal of Forensic Sciences. He was not involved in the Folbigg case.

''I think she's written a very even-handed book based on substantial research and persuasively concludes … that Kathleen Folbigg has been wrongly convicted,'' he said.

Dr Cunliffe says the medical uncertainty that existed at the time of Folbigg's trial and the appeals had since moved to a consensus view: that repeated unexplained infant deaths in a single family can and do occur.

''Based on my findings that the jury was misled about the state of medical research at the time of the Folbigg trial, and coupled with the developments in medical research that have occurred since 2003,

I believe that Kathleen Folbigg's conviction is unsound and should be reviewed,'' she said.